Toluene sulfonic acid treatment of aromatic hydrocarbons



March 1948. R. DOCKENDORFF 2,438,001

TOLUENE SULFONIC ACID TREATMENT OF AROMATIC HYDROGARBONS Filed A ril 19, 1946 rowsms suu-mc ACID SE11 l 25 SETTLING 5 T TANK COOLE/IE No OH TREATMENT .45 ORNEY.

Patented Mar. 16, 1948 7 a UNITED STATES PATENT ornca TOLUENE SULFONIO ACID TREATMENT OF ABOMATIC HYDBOCABBONS Ralph L. Dockendorfl, Goose Creek, Tex, assignor to Standard Oil Development Company, a corporation of Delaware Application April 19, 1946, Serial No. 883,417

1 9.01am. (Cl. 260-674) 2.

The present invention is directed to a method varied over a substantial range and satisfactory for treating normally liquid aromatic hydrocarresults obtained. For example, one part of the ban, feed stock may be intimately contacted with In the production of an aromatic hydrocarbon toluene sulfonic acid in an amount within the it is desirable to subject the aromatic material to 5 range or .2 to parts of the'toluene sulfonic a finishing treatment capable of removing conacid. Similarly. he tim 1 nt ct tween the taminating materials therefrom whereby a prodtoluene sulfonic acid andthe feed stock may be,

i not capable of passing conventional tests is obvaried over a considerable range; it will be found tained without the loss of undue amounts of arothat g o results y vbe in d with the time matic material. As an example of such an un- 10 of contact within t r n of five minutes to finished aromatic fraction may be mentioned the several hours. It will usually be found preferraw toluene stream commercially obtained from. able, however, to contact the aromatic fraction the treatment of petroleum fractions and comwith approximately an equal volume of toluene prising contaminants such as olefin and diolefln sulionic acid and to maintain the materials inof the order of 3% and aromatic hydrocarbon tlmately admixed r a time in rv l Within the of the order of 97%. It is desirable to treat such range of ten minutes to one hour. a feed stock comprising a major portion of aro- The present invention will now be described in matic hydrocarbon and a minor portion of congreater detail in conjun t on With the raw n taminating' material so that it will have a dein which the sole figure is in the form of a di sirably low bromine number and will have a suitaglflmmatic fl et able acid wash color. I Turning now specifically to the drawing, a raw The acid wash color test is described in the toluene feed stock consisting .of appr xim y U. S. Army Toluene Specification 50-11-38D 97% toluene and approximately 3% contaminant, dated February 12, 1943, a low acid wash color 'such as olefin and diolefln. is introduced through indicating the toluene to be of nitration grade. inlet line H and admixed with toluene. sulionic The bromine number test is a measure of the acid flowing through line 12. The source of the olefin content of a hydrocarbon fraction and a toluene sulfonic acid in line l2 will be apparent description of this test method may be found in as the description proceeds. The mixture of U. 0. P. Laboratory Test Methods for Petroleum raw toluene and toluene sulfonic acid is disand its Products, page 186, published by Univercharged into vessel l3 which is commonly dessal 011 Products Co., Chicago, Illinois, 1937. ignated in the art as a time tank and arranged A toluene having an acid wash color test or to allow a sufiicient time of contact between the 0-1 is considered satisfactory for nitration and is feed stock and toluene sulfonic acid to allow the of proper storage stability; the bromine number contaminants to react. From the time tank the should be correspondingly low for the toluene Product of the'reaction is withdrawn through to be used for this purpose. outlet line I [which in turn discharges into set- In accordance with the present invention an tling vessel 15. V aromatic hydrocarbon stream containing a minor In the settling vessel a lighter layer comprisportion of contaminants is brought into contact me 0l11 n .l y ene e lif n c acid a with toluene sulfonic acid in a liquid phase at a 40 separates from a heav r layer p i i toluene temperature of approximately atmospheric or sulfonic acid and toluene. The lighter layer comslightly above atmospheric in order to remove prises approximately equal parts of toluene and the contaminants such as oleflns, diolefins and polymer and is withdrawn through outlet line IS; the like and to obtain a treated aromatic fracthis fraction maybe subjected to further treattlon having a; satisfactory bromine number and ment, not shown, such as distillation in order to satisfactory acid wash color test. recover toluene from the polymer. The heavy As stated heretofore, the aromatic fraction is layer is withdrawn from vessel l5 through line treated in the liquid phase with toluene sulfonic l1 containing a heater I8 which increases the acid. The treatment may be carried out at a temperature of the fraction to approximately temperature within the range of to 150 F. 50 300 F. and the heated fraction is then discharged Usually it will be found desirable to employ a to an evaporating vessel l9. temperature of approximately 85 F. for the treat- In vessel l 9 a heavy fraction which is substanment. tially pure toluene sulionic acid is removed The volume of toluene suli'onic acid contacted through outlet line 20 and passed through pump with the unfinished aromatic feed stock may be 2| and the stream then split with a portion passing through line 22 and returned to the stream flowing in line H upstream from heater l8 and another portion passing through line 23 containing cooler 24 and the cooled stream then entering line I! where it is commingied with the raw feed stock. Make-up toluene sulfonic acid to replace that withdrawn from the system may ,be added through inlet 25.

The lighter, vaporous fraction removed from vessel l9 passes through outlet 26 containing cooler 21 where it is then contacted with sodium hydroxide in unit 28 in a manner well known to the art. Finished product is removed from unit 28 through outlet 29.

The practice of the present invention will be further illustrated by the following examples:

Example 1 A raw toluene fraction, obtained by the treatment of petroleum including the step of extracting with liquid sulfur dioxide a fraction having a bromine number of approximately 2.5 to 3 and an acid wash color of 1-2, was intimately contacted with an equal volume of toluene sulfonic acid at a temperature of 80-90 F. for ten minutes and was then separated from the toluene suli'onic acid by settling under the influence of gravity. The toluene fraction recovered was found to have an acid wash color of 1.

Example 2 A portion of the same raw toluene fraction used in the preceding example was admixed with an equal volume of toluene sulfonic acid and intimately contacted at a temperature of 8090 F. for one hour and the treated toluene fraction then separated from the toluene sulfonic acid fraction by gravity settling. The toluene fraction obtained had an acid wash color of -1 and a bromine number of .01; the bromine number of the raw toluene was in the range of 2.5-3.0.

The acid wash color and bromine number obtained by the treatment in each of the examples given above is considered to be within the proper range to assure that the toluene samples will meet the acid wash color storage stability requirements.

It will be seen that I have described a simple effective manner for treating a feed stock comprising a major portion of aromatic hydrocarbon and contaminated with a minor portion of contaminants which allows the reduction of the contaminants to such an extent that the finished stock will satisfy the usual commercial standards for nitration grade. While I have disclosed specific examples illustrating the invention, it is to be understood that the examples are given only by way of illustration and are not intended to limit the invention in any way.

Having fully described and illustrated the practice of-the present invention, what I desire to claim as new and useful and to secure by Letters Patent is:

1. A method for treating an unfinished normally liquid fraction comprising a major portion of aromatic hydrocarbon and a minor portion of unsaturated straight chain hydrocarbon contaminant including the steps of mixing'said fraction in a liquid state with a suflicient quantity of substantially anhydrous toluene sulphonic 4 acid to form an admixture which will separate into at least two phases upon settling, settling of said admixture to separate it into two immiscible layers one of which is a toluene sulphonic acid layer, withdrawing said toluene sulphonic acid layer and distilling said withdrawn toluene sulphonic acid layer to recover therefrom a finished aromatic fraction substantially free from said contaminant.

l0 2. A method in accordance with claim 1 in perature no greater than 150 F. the said fraction in a liquid state with a sufiicient quantity of substantially anhydrous toluene sulionic acid to cause phase separation upon settling to improve the acid wash color of the toluene and subse- 5 quently settling to recover substantially purified toluene fraction from the acid layer.

5. A method in accordance with claim 4 in which the raw toluene is contacted with substantially an equal volume of toluene sulfonic acid.

30 6. A method for purifying a raw toluene fraction comprising polymer and unsaturated straight chain hydrocarbon contaminants including the steps of forming the raw toluene fraction into a liquid stream, admixing substantially anhydrous toluene sulfonic acid with the stream to form an admixture, subsequently separating the admixture under the influence of gravity to obtain a toluene polymer fraction and a fraction comprising a toluene sulfonic acid 4 and toluene, separately removing the two fractions, distilling the fraction comprising toluene sulfonic'acid and toluene to separate it into an overhead fraction of substantially pure toluene and a bottoms fraction comprising substantially anhydrous toluene sulfonic acid.

7. A method in accordance with claim 6 in which the recovered substantially anhydrous toluene suifonic acid is admixed in sufllcient quantity with the stream of raw toluene to cause phase separation upon settling.

8. A method in accordance with claim 6 in which the toluene sulfonic acid admixed with the raw toluene stream is substantially equal to the volume of the raw toluene.

9. A method in accordance with claim 6 in which the toluene sulfonic acid is contacted with the raw toluene stream at a temperature in the range of 50 to 150 F.

RALPH L. DOCKENDORFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,010,606 Moser (B) Aug. 6, 1935 2,055,416 Moser (A) Sept. 22, 1936 2,200,704. Retalliau May 14, 1940 Friedman July 16, 1946 

